The development of a broad-spectrum vaccine against influenza viruses would represent a tremendous contribution to the available armamentarium against influenza. Recent studies demonstrate the existence of broadly neutralizing anti-influenza antibodies and show, for the first time, that there are regions of the viral hemagglutinin that can mediate broad immunity against influenza viruses. The challenge, now, is to develop a vaccine based on these regions that elicits broad-spectrum immunity in humans. In this proposal, we delineate an experimental approach toward the development of a universal influenza virus vaccine. The basic strategy is to identify epitopes of the hemagglutinin that mediate broad virus neutralization, to subsequently incorporate those epitopes into novel immunogens, and finally to enhance and augment the immunogens by addition of adjuvanting components that will be identified using a human ex vivo experimental system. We will test immunogens and adjuvant preparations in mice and in ferret models of disease. The strategy that we outline in this proposal was developed and refined by way of substantial preliminary experimentation both in the identification of broadly neutralizing antibodies and in the production of prototype broad-spectrum influenza vaccines. Our own preliminary studies, along with the combined expertise of the collaborating investigators, support the feasibility of this proposed work. We strongly believe that our continued efforts in this area are likely to result in an influenza vaccine that provides broad-spectrum protection that is much enhanced over that provided by currently available vaccines. RELEVANCE: The purpose of this proposed work is to generate broadly-protective influenza virus vaccines and to study human immunity to influenza viruses. The experimental approach outlined here was developed and refined during preliminary experiments in which we identified broadly neutralizing antibodies and generated prototype influenza immunogens designed to provide enhanced broad-spectrum coverage over current vaccines. Our preliminary studies along with work from other groups demonstrate proof-of-concept for broad-spectrum influenza virus vaccines and justify major efforts in this area of vaccine design. Project 1: Design of New Immunogens Based on Conserved Epitopes in the Influenza Virus Hemagglutinin Project Leader: Palese, P. DESCRIPTION (provided by applicant): The proposed work is to generate broadly-protective influenza virus vaccines. The basic experimental approach that we will use to accomplish the goal of vaccine generation is divided into two phases. Aim 1 involves characterization of human and murine monoclonal antibodies with broad protective activity against hemagglutinins of distinct influenza virus strains. Efforts will be made to determine the precise region of binding o these broadly-protective antibodies on the hemagglutinin molecule. Aim 2 of this work will involve the design and production of novel vaccine constructs that focus immunity towards those epitopes determined to mediate broad protection. We will construct a set of novel immunogens: several will be based on conserved, continuous, polypeptidic regions of the hemagglutinin, others are based on conformational, discontinuous moieties or on chimeric hemagglutinins. The vaccination strategies will involve the use of DNA, recombinantly purified protein or purified (chimeric) virus. In collaboration with Projects 2 and 3, the vaccine construct will be optimized by use of complementary adjuvant preparations and will be evaluated for efficacy in both mouse and in ferret models of disease. RELEVANCE: Present influenza virus vaccines have to be newly manufactured every year because the circulating influenza virus strains are continuously changing. We are attempting to design novel universal influenza virus vaccines which would be cross-protective against different strains and thus last longer, avoiding the necessity of annual revaccinations; this will e done by first identifying cross-protective monoclonal antibodies (directed against the viral hemagglutinin) and the precise epitopes/sequences they recognize. These epitopes will then be used to guide the design of vaccine constructs which induce cross-protective immune responses against many different influenza virus variants.